CB 750 F2 Old Skool Turbo

[voxonda]

After (almost) finishing my replica racer, starting another build. My second Turbo build, although to be honest the first one was sold before I finished it.
It will be a real Old Skool draw through setup.
This is the victim:

Turbo from Garrett:

Prepped clutch cover with oil return:

Shorter rods from a DOHC750 to achieve right CR.

HD studs to keep it all in one piece:

[Rusty Spokes]

I was thinking about a turbo for mine since it has low compression and low gears. What is your input on that, have you heard, seen, bad or good things about it? I seen one on youtube but its only doing a burn out plus it's supercharge.

[voxonda]

Why has yours low compression and low gears? What type is it?

[TOOLS1]

He has an automatic, and yes they do have lower compression. Also the cam is a perfect grind, for a turbo/supercharger.
What do, you mean, CLUTCH COVER?
TOOLS

[voxonda]

Aha that explains a lot, well knowing that: Just go for it!
Haha, yes it is getting a oem clutch until we solved the last small issues with the dry clutch.
But it gets a deep sump:

[Rusty Spokes]

thanks Tools, I forgot to mentioned it was automatic..sorry. I don't want to steal your thread but I was thinking about a small volvo turbo from the junk yard or something will do but I wanted to make sure before get all in to it! I'm glad the cam is a great start..Thanks!  

[voxonda]

Yes, cams is somewhat different in Turbo engines than in 'normally' aspirated engines. In a Turbo you do not want/need duration, a bit more lift will do just fine.

[Daddyman]

If you pull a turbo from a different engine does the displacement have to be close for it to work?

[voxonda]

you do not want a Turbo too big, 'cause it will not spool. Look for a Turbo from a small car. I use Garrett T2 or 2.5.

[Rusty Spokes]

I always been a S.O.H.C. Honda guy since 91, my best build was a sohc 1.5 with 1.6 vtech head with the activating button on the shifter, I polished and port match the heads to a manifold I also made to fit with R1 carbs, no ecu, msd system with 4 to 1 headers and my street car was a 91 civic hatchback with a japanesse sohc 1.6 ( higher compression and h.p.) and tranny (shorter gears) fully gutted wieghting 1,960lbs w/ quarter tank and me in it (155lbs) I beat a gutted righthand drive 94 prelude 2.2 in that one...good ol days but I'm done that and done with it! My point is anything is possible with Honda, thats why I love them!! But another question, what ecu do you use? I was thinking about using a famous 1988-1991 1.5 dual point injection and have it reprogramed or chromed?  

[voxonda]

I will not use a ecu. A going real Old Skool and use either a S&S, SU or (preferable) a Mikuni HSR carb in my draw through setup.

[voxonda]

And on that carb a K&N, which I had lying around from the previous turbo build.

[samir_nayanajaad]

Im going to be glued to this thread.  If you don't mind would you answer a few questions?

Can you give more details on the engine set up such as target horse power, boost, compression ratio, what turbo is that t2 or 2.5, what cam are you going to use, and any other cool stuff such as that clutch cover that you are planning on?

Any reason your doing a draw through set up, just keeping to the old school set up?(edit: looks like your post above answered this just ignore)

Is this going to be a daily rider or track use bike?


I want to list out about a million questions but don't want you stuck on your computer for a few hours answering them and not working on that bike,

[voxonda]

Thanks for your enthusiasm. I certainly do not mind answering questions.
To begin with it will be a bike suitable for daily driving, so no dragrace like horsepower. My aim is to achieve around 95 to 90 bhp at the rearwheel, so that is considerable over oem numbers.
In order to keep it all payable will not go for extreme boost. CR will be set at 8.0:1. Do not want to use filling beneath the cylinder, so using 1 m/m shorter rods from a DOHC750.
At first will be using the oem cam, but in a later stage might go to Webcam and ask for a special grind.

Cheers, Rob

[samir_nayanajaad]

Thanks for the reply.  One thing I still don't fully understand is the turbo you chose. I'm still very new to all this but have been trying to grasp reading compressor maps and all the math that goes into getting the right sized turbo for a given application.  Could you perhaps link to the specific turbo you have? Im just curios to see the numbers on it and its compressor map.

My first stab at finding a good turbo, for a similar driving type, horse power, and compression ratio, but with it being blow through and with an intercooler is this one

http://www.turbobygarrett.com/turbobygarrett/catelog/Turbochargers/GT15/GT1548_466755_3.htm

[shinyribs]

Poor Samir,I bet you dream of turbos at night,huh?  haha   jk wit ya man

[samir_nayanajaad]

Yeah, like I said lots and lots of time to think.

[voxonda]

Hello Samir,

I am no pro either. Dont get me wrong. To make thing clearer, on my previous build I used a Airresearch/Garrett T2.
On this build I use the TB1903, comes from a Nissan car. It is a small Turbo, but we're talking  120CFM here. Not using new Turbo's, find it a challenge to use 'used' parts and still get it to work. Been looking for the compressor map but cannot find one on the net so far.
# on the compressor A/R .48
# on the Turbine A/R .35

Rob

[samir_nayanajaad]

Well anyone that's willing to share what they have learned to help others gets respect in my book. Keep us updated on this build.

[voxonda]

Although not yet definitely, decided not to go with the F2 engine, but use the crankcase from a F1 I have lying around and build from there. Have taken a couple of days searching for the correct case bolts and the stronger 12.9 bolts that will hold the crankshaft in its place.
Intend to use the 'extra plate' clutch from APE that will give about 20% more friction. Also a oilcooler will be mounted with a thermostate.
Will shoot some pic's tomorrow.